FIG. 1 is a partially exploded bottom view of a conventional disc drive 100 which includes a top cover 140, a bottom cover 150, a loader 110, and a traverse 120. The traverse 120 is set inside of the loader 110 and has a spindle motor and a pickup head disposed on it for rotating a disk and reading data on the disc separately. The top cover 140 covers the top of the loader 110, and the bottom cover 150 covers the bottom of the loader 110 and forms a space with the top cover 140. The traverse 120 can be sealed in the loader 110 by both the top cover 140 and the bottom cover 150.
The disc drive 100 further includes a circuit board 130 on which a central processing chip, a power-supply chip, a memory, and some necessary electronic components are disposed. The circuit board 130 connects electronically with the spindle motor and the pickup head disposed on the traverse 120 for controlling the rotation of the spindle motor and processing the data from the pickup head.
In the conventional disc drive 100, the loader 110 has two side walls 112, and there are several screw holes 116 on the bottom surface of the side walls 112. The circuit board 130 is set on the bottom of the two side walls 112, and then the bottom cover 150 covers the circuit board 130 so that the circuit board 130 is disposed between the bottom cover 150 and the bottom of the two side walls 112. Moreover, the disc drive 100 includes some screws 160 adapted to be inserted through corresponding screw holes 116 for securing the bottom cover 150 to the loader 110.
In the conventional disc drive, due to the limitation of the circuit layout technique, it is difficult to reduce the area of the circuit board, so the width of the circuit board is designed to be similar to the width of the loader. Therefore, the circuit board can be set on the side walls of the loader and secured by screws between the bottom cover and the loader, as shown in FIG. 1.
As technology progresses, the layout area of the chips and the circuit on the circuit board are gradually reduced. However, even if the circuit layout area can be reduced, the size of the circuit board cannot be reduced since the circuit board needs to be set on the side walls of the loader. In other words, the width of the circuit board still has to be similar to the width of the loader so as to assemble the circuit board on the loader in the traditional way, so that the cost of the circuit board does not decrease even as improvements are made in the relevant technical field. Therefore, if the size of the circuit board can be reduced without increasing the cost of the disc drive and without changing the original structure of the disc drive, it will not only decrease the cost of the circuit board, but can also increase market competition.